1. Field of the Invention
This invention relates to a process for disposing of sewage sludge with the aid of material having a BTU energy input.
2. Description of the Prior Art
The prior art which best illustrates the disposal of sewage sludge is found in Colby et al U.S. Pat. No. 2,032,402 of Mar. 3, 1936 which provisionally may introduce pulverized coal to facilitate burning of the sludge. O'Mara U.S. Pat. No. 2,066,418 of Jan. 5, 1937 disposed of sludge directly in a furnace after mixing the wet sludge with dried sludge. There are two Dundas et al U.S. Pat. No. 2,148,447 of Feb. 28, 1939 and U.S. Pat. No. 2,148,981 of Feb. 28, 1939 which disclose elaborate apparatus for sewage waste disposal using coal to assist in the combustion of the waste, where the coal is prepulverized or powdered in advance of being introduced into the system.
Additional prior art is represented by Riepl et al U.S. Pat. No. 3,109,392 of Nov. 5, 1963 which introduces an outside fuel after the waste refuse has been comminuted; and Williams U.S. Pat. No. 4,245,570 of Jan. 20, 1981 which collects dried sludge and burns it with the aid of outside fuel for effecting the drying of the incoming sludge as it is being ground.
It has not been recognized by the workers in this art of disposing of sewage sludge that as the water is evaporated or removed from the initial raw sewage sludge, by whatever method, the thickening of the sludge results in a very sticky mass which easily plugs the apparatus to the extent that the disposal is retarded with excessive down time of the apparatus. Experience has shown that the sludge in losing water forms a coating on the surfaces of conduits and within the processing mills which reduces the efficiency of the apparatus. These unwelcome characteristics are not overcome by the practices taught by the known prior art as the outside fuel is not introduced until late in the operating cycle of the apparatus, and as a result the foregoing problems and other related or secondary problems which have accrued have not been successfully overcome.